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B. P. CLARK. ELEGTRODEPOSITION OF LEAD.

No. 598,313. Patented Feb. 1,1898.

.ERNEST P. CLARK, OF NEW YORK, N. Y., ASSIGNOR OF ONE-HALF TO CHARLES S. CAMPBELL, OF SAME PLACE.

ELECTRODEPOS'ITION OF LEAD.

SPECIFICATION forming part of Letters liatent No.598,313, dated February 1, 1898. Application filed June 8,1897 fierialNo. 639,908. (Specimens) To all whom it may concern.-

Be it known that I, ERNEST P. CLARK, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Electrodeposition of Lead, of which the following is a full, clear, and exact description.

This invention relates to the production of a peculiar form of finelydivided metallic lead by means of electrodeposition; and it consists of certain novel means and methods of preparing a bath or solution from which a form of finelydivided lead heretofore unknown is produced by electrolysis, to which form Ihave given the title of feathery lead,

- on account of its peculiar appearance in the depositing solution.

The accompanying drawing shows a sectional view of an electrodepositing cell equipped for operation in accordance with my invention. a

If a solution be made of dilute acetic acid, nitric acid, acetate of lead, or of any of the well-known solvents of lead and an anode of metallic lead be immersed in the said solution, a cathode of lead or other suitable material being also placed in the solution, and an electric current be sent through the bath or solution, a deposit of slate-colored lead withoutmetallic luster and devoid of metallic appearance or tenacity is produced upon the cathode. This deposit has been aptly termed frothy lead, and, to my knowledge, is the only form in which lead in or approaching the metallic state has been deposited by the aid of electricity.

The lead produced by precipitating the metal from its acetic solution by means of metallic zinc is another variety of finely-divided lead and is known as spongy lead. This variety has more of a metallic appearance than the frothy lead and may be compressed into somewhat solid and firm masses or blocks, but is not a bright and lustrous material, nor has it the tenacity of the material formed by my process, which I will now proceed to describe. 1

In preparing my solution I take water and acetate of lead-about one pound ten ounces of acetate of lead to each gallon of water. A

ical action now taking place the lead contained in the solution is precipitated upon the zinc and a portion of the zinc is dissolved, replacing the lead in the solution. At the same time as lead is being removed the solution will rapidly dissolve the portion of acetate of lead contained in the cotton bag, the solution thus growing more dense or of greater specific gravity. After about ten or twelve hours all the acetate has been dissolved from the bag, which can then be removed. The zinc plates should also be re moved and the heavy deposit of spongy lead detached. Upon replacing the zinc plates a new deposit of spongy lead will rapidly form.

As lead is removed from the solution and zinc dissolved therein the specific gravity of the solution will become graduallyless. This process, which is a change from acetate of lead to acetate of zinc, should be stopped by removing the zinc plates before all the lead is removed from the solution.

I have found in practice that in using the above proportions of acetate and water the zinc should be removed and the process of conversion stopped when the gravity of the solution is reduced to 18 or 19 of Baums hydrometer. The solution willnow be of a light-brown color, or if sulfate of lead is contained as an impurity in the acetate there may be a milky turbidness also present which will subside in a few hours and do no harm. If now a lead anode and a cathode of lead or other suitable material be immersed in the liquid and a current of electricity be sent through it, there will usually appear in a few minutes bright deposits of metallic lead upon the cathode and no trace of the slate-colored frothy lead mentioned above. Sometimes,

however, the first deposit which appears is the frothy material, and at other times both kinds of deposit appear. The anode and cathode should be first placed vertically until it is certain that the frothy deposit is not being formed, after which the disposition about to be described may be adopted.

I find in practice that the frothy form of deposit is rarely seen in this solution unless its specific gravity is too low. The gravity I have mentioned is that which I have found best adapted to the purpose, but it may be much lower, if desired, and good results obtained. One way I have found for obtaining a good working solution of a low gravity is to use about half the amount of acetate of lead above mentioned and then remove nearly all of the lead from the solution by means of V zinc, as described. The vertically-arranged anode and cathode being now placed in" the solution and the current passed, the anode is gradually dissolved and a diffused deposit of the frothy form appears and must be removed from the cathode from time to time. Aftera time, varying from one or two to forty-eight or more hours,.a bright deposit will be observed on the lower part of the cathode, which is the desired deposit of feathery lead. Continuing the current and removing the deposit from time to time there Will grad ually be more of the feathery bright deposit and less of the dull slate-colored deposit, until finally the whole of the lead deposited will be bright, silvery, and feathery in appearance. A little pulverized acetate of lead-say an ounce to the gallon-added to the solution after the bright deposit first appears will hasten the process. By this means a solution as light as 8 or 10 Baum can be obtained which will work perfectly; but I prefer to use it of a higher density, as first described, as being easier to form and of lower electrical resistance.

The solution being formed in either of the above ways I place it in a large glass jar or tank a, holding several gallons. A cathode Z), consisting of a disk of thin sheet-lead, is placed in the bottom of the tank, with an insulated conductor 1), extending above the liquid, soldered to the disk. A heavy anode c, of cast or pig lead, is suspended in the solution near its surface and the current passed. The anode gradually dissolves and very soon a deposit of lead of the general form of very small feathers is seen to grow upon the oath ode and gradually increases in heaps or piles, starting at the edges of the cathode and grad uall'y'covering all its surface, filling the jar several inches. During the first few hours the solution gradually loses its brown tinge and becomes perfectly clear. The deposit becomes of a silvery brightness and the re semblance of the crystals to small feathers becomes very striking. The deposit should be gently pushed down with a wooden rod from time to time until sufficient of the material has been made. The density of the .current tobeused cannot be definitely stated, as I have found that good results have been obtained with a current ranging anywhere from one to sixteen amperes per square foot of anode. If a portion of this material be removed and examined, it will be found to be interlaced like felt or oakum, and in pulling it apart its tenacity is quite remarkable, being very much greater than that of spongy lead deposited from acetate-of-lead solution. If compressed in the hand or by other means, it forms a strong tough mass, and when fresh is very bright and silvery in appearance, but of course soon turns dull from exposure to the air. This product in fact seems essentially to be a fibrous material free from all oxids and other impurities.

As far as I understand the chemistry of the solution it consists of a mixture of acetate of lead and acetate of zinc, yet I have failed to obtain any such results from an ordinary mixture of these solutions. I have also tried unsuccessfully to use a solution of acetic acid by dissolving'zinc in it electrolytically and adding lead by the same process. The only way I have found to produce this peculiar form of deposited lead is by the solution produced as above described. I have also thought that as the solution contains a large amount of zinc some zinc may be deposited with the lead, but so far I have been unable to find any trace of it in the material deposited. I believe this material will be largely usedfor the active material of storage-battery plates, for which purpose it possesses many advantages. I do not limit myself, however, to this or any other particular use or application of my new material, but claim its use for all purposes wherein lead in an extreme state of subdivision may be employed and where a finelydivided lead of lustrous surface and feathery orfibrous nature is desirable.

Having thus described my invention, I claim-e 1. The process of producing finely-divided lead which consists in first partially changing an acetate-of-lead solution into an acetate-ofz'inc'solution and then depositing lead by passing a current of electricity from a lead anode through the solution to a cathode,.substanti'ally as described.

2. The process of producing finely divid'ed lead, which consists in first putting zinc into a solution of acetate of lead and allowing it to remain until a portion of the lead in the solution has been deposited and zinc gone into solution, and then passing a current of electricity from a lead anode through the solution to deposit the finely-divided lead upon the cathode, substantially as described.

3. The process of producing finely-divided lead of a feathery and fibrous nature which consists in first dissolving acetate of lead in water, then immersing in this solution a plate of zinc and allowing it to remain until a portion of the lead has been deposited and a portion of the zinc substituted therefor in the solution then passing a current of electricity through the solution from a lead anode to a cathode until the deposit of lead on the oathode changes from a frothy appearanceto a passing a current of electricity through the 1g feathery appearance and then continuing the electrodeposition of the lead upon the oathode horizontally arranged in the lower portion of the solution, substantially as described.

4. The process of electrodepositing lead, consisting in first displacing a portion of the lead in a lead acetate solution and substituting therefor some other material, and then solution from a lead anode.

In testimony whereof I subscribe my signature in presence of two witnesses.

ERNEST P. CLARK.

WVitnesses:

FRANK S. OBER, HARRY BAILEY. 

